/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2006, Red Hat Middleware LLC, and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package test.dbc.stack;

/**
 *
 * @author <a href="mailto:kabir.khan@jboss.org">Kabir Khan</a>
 * @version $Revision: 57186 $
 * @@org.jboss.aspects.dbc.Dbc
 * @@org.jboss.aspects.dbc.Invariant ({"!$tgt.isEmpty() implies $tgt.top() != null", "$tgt.isEmpty() implies $tgt.elements.size() == 0"})
 */
public interface Stack
{
   /**
    * @@org.jboss.aspects.dbc.PreCond ({"$0 != null"})
    * @@org.jboss.aspects.dbc.PostCond ({"!$tgt.isEmpty()", "$tgt.top() == $0"})
    */
   void push(Object o);

   /**
    * @@org.jboss.aspects.dbc.PreCond ({"!$tgt.isEmpty()"})
    */
   Object pop();

   /**
    * @@org.jboss.aspects.dbc.PreCond ({"!$tgt.isEmpty()"})
    */
   Object top();

   boolean isEmpty();
}